A graphene-based biosensor for detecting microRNA with augmented sensitivity through helicase-assisted signal amplification of hybridization chain reaction

•Combining the different affinity of ssDNA and dsDNA on GO with the unwinding character of RecQE on incomplete dsDNA structure, molecular mechanism of helicase on graphene-based platform was explored to detect the let-7a miRNA.•Helicase can rapidly promote the hybridization chain reaction triggered by let-7a on the surface of GO and the helicase-assisted HCR/GO sensing platform dramatically shortens the miRNA detection time from 4h to 50min.•The sensitivity of this sensing platform is 2 orders of magnitude higher than those without the enzyme. Most nucleic acid biosensors are based on hybridization binding models. During reactions, target molecules are hybridized with probes, inducing intensive signal changes. The molecular mechanism of nucleic acid related enzymes for new hybridization reaction systems based on graphene oxide (GO) has far-reaching significance, especially of helicases. This paper proposes a helicase-assisted GO-based reaction platform for microRNA (miRNA) detection. In this work, the detection platform was found capable for shortening the detection duration, dramatically from 4h to 50min, and its limit of detection for miRNA was calculated to be 4.2 fM as per 3σ rule. The sensitivity of the helicase-assisted HCR/GO sensing platform was 2 orders of magnitude higher than common HCR/GO sensing platform without enzymes. Meanwhile, the extensive applicability of helicases to hairpin probes makes the enzyme-associated platform in vast use to improve the detection efficacy of other nucleic acid molecules.